linux-kernel - Re: [PATCH v3 2/2] i2c: New bus driver for the Qualcomm QUP I2C controller

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Message-ID: <5306BFC4.5000005@elopez.com.ar>
Date:	Thu, 20 Feb 2014 23:53:56 -0300
From:	Emilio López <emilio@...pez.com.ar>
To:	Bjorn Andersson <bjorn.andersson@...ymobile.com>
CC:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Rob Landley <rob@...dley.net>,
	Wolfram Sang <wsa@...-dreams.de>,
	Grant Likely <grant.likely@...aro.org>,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
	linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Stephen Boyd <sboyd@...eaurora.org>,
	"Ivan T. Ivanov" <iivanov@...sol.com>,
	Andy Gross <agross@...eaurora.org>
Subject: Re: [PATCH v3 2/2] i2c: New bus driver for the Qualcomm QUP I2C controller

Hi Bjorn,

El 20/02/14 21:38, Bjorn Andersson escribió:
> This bus driver supports the QUP i2c hardware controller in the Qualcomm SOCs.
> The Qualcomm Universal Peripheral Engine (QUP) is a general purpose data path
> engine with input/output FIFOs and an embedded i2c mini-core. The driver
> supports FIFO mode (for low bandwidth applications) and block mode (interrupt
> generated for each block-size data transfer).
>
> Cc: Andy Gross <agross@...eaurora.org>
> Cc: Stephen Boyd <sboyd@...eaurora.org>
> Signed-off-by: Ivan T. Ivanov <iivanov@...sol.com>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...ymobile.com>
> ---

I'm not familiar with the subsystem nor the hardware, so I had a look 
around for general stuff. I have some minor comments to make on the 
probe code.

(snip)
> +static int qup_i2c_probe(struct platform_device *pdev)
> +{
> +	static const int blk_sizes[] = {4, 16, 32};
> +	struct device_node *node = pdev->dev.of_node;
> +	struct qup_i2c_dev *qup;
> +	unsigned long one_bit_t;
> +	struct resource *res;
> +	u32 val, io_mode, hw_ver, size;
> +	int ret, fs_div, hs_div;
> +	int src_clk_freq;
> +	int clk_freq;
> +
> +	qup = devm_kzalloc(&pdev->dev, sizeof(*qup), GFP_KERNEL);
> +	if (!qup)
> +		return -ENOMEM;
> +
> +	qup->dev = &pdev->dev;
> +	init_completion(&qup->xfer);
> +	platform_set_drvdata(pdev, qup);
> +
> +	clk_freq = 100000;
> +	if (!of_property_read_u32(node, "clock-frequency", &val))
> +		clk_freq = val;

val will be modified only if no error occurs, so you may rewrite this 
bit as

+	u32 clk_freq = 100000;
...
+	of_property_read_u32(node, "clock-frequency", &clk_freq)

> +
> +	/* We support frequencies up to FAST Mode (400KHz) */
> +	if (clk_freq <= 0 || clk_freq > 400000) {

And you can drop the < check when it's unsigned.

> +		dev_err(qup->dev, "clock frequency not supported %d\n",
> +			clk_freq);
> +		return -EIO;

EIO?

Cheers,

Emilio
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